The frequency and volume of transplacental hemorrhage that occurs with threatened abortions is unknown. The use of Rh immune globulin for such patients is therefore undefined. We studied the incidence and quantity of transplacental hemorrhage in patients with threatened abortions and in a control population of patients presenting in the first 20 weeks of pregnancy without a history of bleeding. Using the Kleihauer-Betke test, the incidence of transplacental hemorrhage in our control and study population was not statistically different.